Citric acid has the molecular formula C6H8O7 so you can add the molar masses of the elements from the periodic table. C has a molar mass of 12.01 g/mol, H has 1.01 g/mol and O has 15.999 g/mol. Now you calculate the total molar mass= (6*12.01 + 8*1.01 + 7*15.999). This yields a molar weight of 192.124 g/mol (anhydrous)
Answer: 0.004 moles
Explanation:
Amount of substance= mass/ molar mass
Mass= 250mg or 0.25g
Molar mass= 58.44gmol-1
Amount= 0.25/58.44
= 0.004 moles
The researcher may first weight the beaker with water and then start to heat the water to a constant temperature, for example 30 °C and then start adding salt and stirring. He should add salt slowly until solid salt starts to become visible and the solution starts becoming cloudy. When this happens, he should quickly weigh the beaker. The increase in mass is the mass of salt dissolved at that temperature.
The procedure is then repeated but at an increased temperature until 5-6 temperatures have been tested.
Student B because it requires a hypothesis
Answer:
cellular respiration
Explanation:
All exergonic processes produced in the cell, through which substances oxidize and chemical energy is released, are grouped under the name of cellular respiration, but to break down an organic molecule the cells employ, mainly dehydrogenations that can be carried carried out in the presence or absence of atmospheric O2 oxygen. There are therefore two types of breathing: aerobic respiration and anaerobic respiration. The latter also called fermentation.
Aerobic respiration (oxidative phosphorylation)
- Use molecular O2.
- It degrades glucose to CO2 and H2O
- Exergonic
- Recovers about 50% of chemical energy
- Present in most organisms.
- It uses enzymes located in the mitochondria.
